JavaScript Form Field Value Update Dilemma

I'm doing an ajax call to a remote php file... it returns a value fine,
and even enters a value into a text field on my form. The problem is,
right after the function call to the ajax function, I do an alert of
what the field value is, and it doesn't recognize the field value has
been changed. Two caveats:

1 - It will recognize the last call's change
(if I run it a 2nd time, it'll see the 1st call changes)
onBlur="ajaxCall(document.form1);alert(document.form1.ajax Field.value);">

2 - It'll recognize the current call's change if I set a 2 second
timeout
onBlur="ajaxCall(document.form1);setTimeout('checkFields(d ocument.form1)',2000);">

It seems, although I can see the text field getting updated,
programmatically speaking, it isn't reflecting it until everything is
done... including any alerts and such.

It's weird seeing the empty alert popup, when I can see the value in
the text field underneath it.